Seasonal dynamics of hydrogen isotope fractionation in mangrove Aegiceras corniculatum lipids

Description

This dataset includes the concentrations of n-alkanes and n-fatty acids, as well as the hydrogen and oxygen isotope compositions from various water sources in the mangrove species Aegiceras corniculatum. These water sources include surface water (SW), pore water (PW), xylem water (XW), and leaf water (LW). The dataset also highlights fractionation occurring at key physiological stages: infiltration between surface and pore water (αPW-SW), water uptake from pore water to xylem (αXW-PW), transpiration between leaf and xylem water (αLW-XW), and biosynthesis between mangrove lipids (n-fatty acids and n-alkanes) and leaf water (αLipid-LW). Additionally, it shows the net fractionation between mangrove lipids and pore water (αLipid-PW).

Steps to reproduce

1. Study Site and Sample Collection Location: Samples were collected from the Zhanjiang estuary, where distinct dry and wet seasons are characteristic of tropical and subtropical climates. Sampling Periods: Sampling occurred during both the dry and wet seasons to capture seasonal variations in environmental conditions. Sample Types: Leaf samples from the mangrove species Aegiceras corniculatum were collected, along with surface water, pore water (from sediment), xylem water, and leaf water for isotopic comparison. 2. Water Sample Collection Surface Water (SW): Collected directly from the estuary. Pore Water (PW): Extracted from sediment using a syringe at a depth of 0-10 cm. Xylem Water (XW): Obtained by cutting stems and immediately sealing them in glass vials to prevent evaporation. Leaf Water (LW): Isolated by cryogenic vacuum distillation from the leaves immediately after collection. 3. Lipid Extraction and Analysis Lipid Extraction: Leaf waxes were extracted from leaf samples using an organic solvent extraction method. Separation of Lipid Classes: n-Alkanes and n-fatty acids were separated using silica gel column chromatography. Quantification: Concentrations of n-alkanes and n-fatty acids were quantified using gas chromatography-flame ionization detection (GC-FID). 4. Isotope Analysis Hydrogen Isotope Ratios (δ²H): Measured for n-alkanes and n-fatty acids using gas chromatography coupled to isotope ratio mass spectrometry (GC-IRMS). Water Isotope Ratios (δ²H and δ¹⁸O): The hydrogen and oxygen isotope compositions of surface water, pore water, xylem water, and leaf water were measured using EA Isolink-253 Plus (Thermo Scientific). 5. Data Interpretation Fractionation factors between different water pools (αPW-SW, αXW-PW, αLW-XW) were calculated using isotopic composition data. Net hydrogen isotope fractionation between mangrove leaf lipids and different water sources was calculated for both the dry and wet seasons. Trends in hydrogen isotope fractionation were analyzed to determine the effects of salinity and seasonality on A. corniculatum physiology and lipid biosynthesis. 6. Software and Data Analysis Data processing and statistical analysis were conducted using OriginLab and R software. Regression analyses were performed on both platforms to assess the relationship between salinity and hydrogen isotope fractionation. Figures illustrating the δ²H and δ¹⁸O values and fractionation factors were created using OriginLab. 7. Reagents and Instruments Solvents: Dichloromethane and methanol for lipid extraction. Instruments: Gas chromatograph for lipid analysis, isotope ratio mass spectrometer for δ²H measurements, and EA Isolink-253 Plus for water isotope measurements. Vials and Syringes: Used for collecting water samples and sealing plant stems to avoid isotopic alteration.

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